Would please give me some advice for the following question.?

The buyer signed the contract below-after a week he wanted to back out and give me a $1000. please give me some advice. Thank you.

1. Received from the Buyer, J Smith, the sum of $7,500.00 evidenced by personal check, payable to T Wu, to be held undeposited until acceptance of this offer as a deposit toward acquisition of the following:

Terms: Buyer to pay the purchase price as follows:
Cash down payment $7,500.00
Final payment 7,500.00

Total purchase price is $15,000.00


2. Final payment will be made on the delivery of the property, with the passing smog check, not later than 5 days after the date of the initiation of the cash down payment.

3. Itemized inventory of the personal property included in the sale to be handed to Buyer on acceptance. Title to be vested in Buyer shall be recorded on the date of delivery.

4. This sale is final, free of liens and encumbrances of any kinds.

p/s-the buyer note: upon approval of all permits & business license. But he did not doing anything.
The seller deposited the check of $7500.